(a) Field of the Invention
The present invention relates to a heat dissipation module, and in particular, to a heat dissipation module having externally exposed fins.
(b) Description of the Prior Art
Plastic Ball Grid Array (PBGA) is a packaging technique for integrated circuits and is employed in mass production manufacturing process. First, the wafer (5a) is milled, cut and adhered onto substrate 2a, after a lining process, the aluminum pad of the wafer 5a is connected to the welding line connection leg on the substrate. A gold line 6a is used for communication. The printed circuit board of the substrate 2a is connected to a tin ball connection leg at one side of the substrate 2a. Next, a synthetic resin rubber body 7a is used for packaging to protect the wafer 5a and the gold line 6a. A welding ball 4a containing zinc, lead alloy is implanted onto the tin ball connection leg. Finally, cut off the remaining portion of the substrate 2a. A Plastic Ball Grid Array product is finally obtained. This Plastic Ball Grid Array product is welded to a main computer board 3a to complete the connection of the electronic parts to the main computer board.
In application, the wafer on the substrate produces extreme heat during operation. Thus, a heat dissipation plate having high heat conduction and electrical conduction property is introduced at the top of the wafer of the Plastic Ball Grid Array and connecting the connection leg of the heat dissipation plate, and the ground connection of the PLASTIC BALL GRID ARRAY substrate. Thus, the interior of the heat dissipation plate is used to absorb heat source of the wafer and to dissipate heat energy via the surface of the heat dissipation plate.
In view of the conventional heat dissipation plate being a simple cap-like structure (referring to FIG. 1), a fairly thick layer of synthetic resin rubber body (two times the thickness of a wafer) is mounted in between the heat dissipation plate and the wafer, the heat energy produced by the wafer can reach the heat dissipation plate by the conduction of the synthetic resin rubber body so as to dissipate heat. However, the synthetic resin rubber body is not a good conductor of heat and the heat from the wafer has to pass through the thick synthetic rubber body in order to attain the heat dissipation plate for heat dissipation. Thus, the heat dissipation efficiency is limited.
Thus, the Plastic Ball Grid Array product obtained by this method needs appropriate heat dissipation blades to adhere to the conventional heat dissipation plate so as to dissipate heat. However, to implement this method, the conventional heat dissipation plate is adhered with a dual layer rubber. Generally the heat transfer coefficient of the dual layer rubber is not high, and thus, the entire heat dissipation effect is reduced, and it does not improve heat dissipation. After some period of application, the rubber body is hardened and cracked as a result of heat, and the externally mounted blades will be dislocated.